Resolves: bz2025860
Upstream: git.kernel.org/pub/scm/utils/kernel/kexec/kexec-tools.git
commit 186e7b0752d8fce1618fa37519671c834c46340e
Author: Alexander Egorenkov <egorenar@linux.ibm.com>
Date: Wed Dec 15 18:48:53 2021 +0100
s390: handle R_390_PLT32DBL reloc entries in machine_apply_elf_rel()
Starting with gcc 11.3, the C compiler will generate PLT-relative function
calls even if they are local and do not require it. Later on during linking,
the linker will replace all PLT-relative calls to local functions with
PC-relative ones. Unfortunately, the purgatory code of kexec/kdump is
not being linked as a regular executable or shared library would have been,
and therefore, all PLT-relative addresses remain in the generated purgatory
object code unresolved. This in turn lets kexec-tools fail with
"Unknown rela relocation: 0x14 0x73c0901c" for such relocation types.
Furthermore, the clang C compiler has always behaved like described above
and this commit should fix the purgatory code built with the latter.
Because the purgatory code is no regular executable or shared library,
contains only calls to local functions and has no PLT, all R_390_PLT32DBL
relocation entries can be resolved just like a R_390_PC32DBL one.
* https://refspecs.linuxfoundation.org/ELF/zSeries/lzsabi0_zSeries/x1633.html#AEN1699
Relocation entries of purgatory code generated with gcc 11.3
------------------------------------------------------------
$ readelf -r purgatory/purgatory.o
Relocation section '.rela.text' at offset 0x6e8 contains 27 entries:
Offset Info Type Sym. Value Sym. Name + Addend
00000000000c 000300000013 R_390_PC32DBL 0000000000000000 .data + 2
00000000001a 001000000014 R_390_PLT32DBL 0000000000000000 sha256_starts + 2
000000000030 001100000014 R_390_PLT32DBL 0000000000000000 sha256_update + 2
000000000046 001200000014 R_390_PLT32DBL 0000000000000000 sha256_finish + 2
000000000050 000300000013 R_390_PC32DBL 0000000000000000 .data + 102
00000000005a 001300000014 R_390_PLT32DBL 0000000000000000 memcmp + 2
...
000000000118 001600000014 R_390_PLT32DBL 0000000000000000 setup_arch + 2
00000000011e 000300000013 R_390_PC32DBL 0000000000000000 .data + 2
00000000012c 000f00000014 R_390_PLT32DBL 0000000000000000 verify_sha256_digest + 2
000000000142 001700000014 R_390_PLT32DBL 0000000000000000
post_verification[...] + 2
Relocation entries of purgatory code generated with gcc 11.2
------------------------------------------------------------
$ readelf -r purgatory/purgatory.o
Relocation section '.rela.text' at offset 0x6e8 contains 27 entries:
Offset Info Type Sym. Value Sym. Name + Addend
00000000000e 000300000013 R_390_PC32DBL 0000000000000000 .data + 2
00000000001c 001000000013 R_390_PC32DBL 0000000000000000 sha256_starts + 2
000000000036 001100000013 R_390_PC32DBL 0000000000000000 sha256_update + 2
000000000048 001200000013 R_390_PC32DBL 0000000000000000 sha256_finish + 2
000000000052 000300000013 R_390_PC32DBL 0000000000000000 .data + 102
00000000005c 001300000013 R_390_PC32DBL 0000000000000000 memcmp + 2
...
00000000011a 001600000013 R_390_PC32DBL 0000000000000000 setup_arch + 2
000000000120 000300000013 R_390_PC32DBL 0000000000000000 .data + 122
000000000130 000f00000013 R_390_PC32DBL 0000000000000000 verify_sha256_digest + 2
000000000146 001700000013 R_390_PC32DBL 0000000000000000 post_verification[...] + 2
Corresponding s390 kernel discussion:
* https://lore.kernel.org/linux-s390/20211208105801.188140-1-egorenar@linux.ibm.com/T/#u
Signed-off-by: Alexander Egorenkov <egorenar@linux.ibm.com>
Reported-by: Tao Liu <ltao@redhat.com>
Suggested-by: Philipp Rudo <prudo@redhat.com>
Reviewed-by: Philipp Rudo <prudo@redhat.com>
[hca@linux.ibm.com: changed commit message as requested by Philipp Rudo]
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Simon Horman <horms@verge.net.au>
v2:
- Moved patch 601 -> 401
Signed-off-by: Philipp Rudo <prudo@redhat.com>
Acked-by: Coiby Xu <coxu@redhat.com>
Philipp Rudo